The present invention relates to novel catalysts of metals preferably transition metals and to the processes for using such catalysts for olefin polymerization. The catalyst contains at least one phosphinimine center, and a carbon atom or an alkenyl radical bonded to the metal to form a metal heteroatom alkyl bond or a carbene structure, respectively.
Currently there is increasing interest in catalysts of transition metals having novel structures.
Recently there has been significant interest in Brookhart""s ligand which may complex later transition metals to form a catalyst useful in an olefin polymerization process. Such complexes are disclosed, for example in World Patent Application 96/23010 jointly in the names of the University of Carolina at Chapel Hill and E.I. DuPont published Aug. 1, 1996. The Brookhart et al patent application does not teach the complexes of the present invention.
The recent paper (Chem. Comm (1998) p. 849) by Gibson and coworkers at Imperial College UK (and BP) teach complexes having a novel structure that is dissimilar to the complexes of the present invention. It is postulated that the complexes of Gibson et al. will have utility in the polymerization of certain monomers such as alpha olefins.
There has been a great deal of work recently by both Exxon in the field of metallocene chemistry and by the Dow Chemical Company in single site constrained geometry complexes. As far as applicant has been able to determine none of the chemistry proposed by either Exxon or Dow contain a carbene structure or a constrained alkyl carbon bonded to a transition metal. There are several patents relating to amidinato complexes of transition metals which are suitable for the polymerization of various olefins. U.S. Pat. No. 5,502,128 issued Mar. 26, 1996, assigned to University of Massachusetts, teaches such complexes may be used to polymerize vinyl aromatic monomers; and U.S. Pat. No. 5,707,913 issued Jan. 13, 1998, assigned to BASF, teaches such compounds may be used to polymerize olefins. Neither of these patents disclose complexes of the structure of the present invention.
U.S. Pat. No. 5,557,023 issued September 1996 teaches the use of some complexes of transition metals to oligomerize lower alpha olefins such as ethylene to higher olefins such as hexene and the like. The complexes of the patent do not contain a carbene structure or substituted carbon bonded to the transition metal.
Copending U.S. patent application Ser. No. 09/375,943 filed Aug. 17, 1999 in the name of R. G. Cavell et al. discloses the complexes useful in the catalyst of the present invention.
U.S. Pat. No. 6,060,568 issued May 9, 2000 in the name of the Applicant discloses complexes similar to those of the present invention except that the complexes contain only one R7 and one R8 substituent. The present invention provides for more than one R7 or R8 substituents. The sum of the subscripts a and b is a whole number greater than 2 and up to the sum of the valence and co-ordination number of the metal (i.e. both the electrovalence and coordinate valence).
Applicant has been unable to identify any prior art disclosing the catalyst of the present invention for the polymerization of olefins.
The present invention provides a process for the polymerization of one or more C2-12 alpha olefins in the presence of a complex selected from the group consisting of a complex of formula I: 
wherein M is a metal atom; R1, R2, R3 and R4 are independently selected from the group consisting of a saturated or unsaturated straight chained, branched or cyclic hydrocarbyl radical which is unsubstituted or substituted by one or more substituents selected from the group consisting of a halogen atom and a C1-6, most preferably a C1-4 alkyl radical; R7 and R8 are independently selected from the group consisting of a hydrogen atom, a halogen atom, an amide of the formula xe2x80x94NR1R2, an imide of the formula xe2x95x90NR1, an alkoxide or aryl oxide group of the formula xe2x80x94OR1, a siloxy group of the formula xe2x80x94OSi(R1)3 wherein R1 and R2 are defined above, and a saturated or unsaturated straight chained, branched or cyclic hydrocarbyl radical which is unsubstituted or substituted by a halogen atom or a C1-6 alkyl radical and a Lewis base (neutral coordinating ligands) which may contain a donor heteroatom including but not limited to ethers, tertiary amines, tertiary phosphines and cyclic amines; a and b are integers and a+b is an integer greater than 2 up to the sum of the valence and co-ordination number of M; and each R5 is independently selected from the group consisting of radicals selected from the group consisting of saturated and unsaturated straight chained, branched and cyclic hydrocarbyl radicals, preferably C1-15 saturated or unsaturated straight chained, branched or cyclic hydrocarbyl radicals, most preferably C1-8 straight or branched alkyl radicals, C6-12 cyclic aliphatic or aromatic radicals, radicals of the formula Si(R6)3 wherein each R6 is independently selected from the group consisting of saturated or unsaturated straight chained, branched or cyclic hydrocarbyl radicals, preferably C1-10 saturated or unsaturated straight chained, branched or cyclic hydrocarbyl radicals and radicals of the formula III: 
wherein R9, R10, R11 and R12 are independently selected from the group consisting of a hydrogen atom, a fluorine atom, a NO2 radical, a C1-6 alkyl radical and a C8-12 aryl radical; E is an endocyclic nitrogen atom or a Cxe2x80x94CN group; and R14 is selected from the group consisting of a hydrogen atom, a sulfur atom, an oxygen atom, an amido radical which is unsubstituted or may be substituted by C1-20 alkyl radical, preferably a C1-6 alkyl radical or a radical of the formula xe2x80x94Si(R6)3 wherein R6 is as defined above, a C1-20 hydrocarbyl radical, a C6-12 aromatic radical and a radical of the formula III as defined above, each of which may contain one or more functional groups including a heteroatom acting as a Lewis base; and optionally R14 taken together with the metal may form a ring; and an activator at a temperature from 20 to 250xc2x0 C. and at a pressure from 15 to 15,000 psi.
The present invention also provides a complex of formula I: 
wherein M, R1, R2, R3, R4, R5, R7, R8, R14, a and b are as defined above.